Exhaust gas recycle (EGR) is the principal technique used for control of spark ignition (SI) NOx emissions. The EGR gases are used to help reduce the combustion chamber temperatures, thus lowering the NOx that is produced during the combustion process. An EGR flange is used to introduce the EGR gases into the airflow stream of the engine intake system through an intake manifold to distribute the EGR gases equally. The EGR gases can have temperatures of up to 275xc2x0 C. and higher, depending on the percentage of EGR gas that is being introduced into the airflow stream. For an aluminum manifold, this high temperature for the EGR gases is not a problem. The EGR flange can be manufactured in one piece because the flange area that mates with the aluminum manifold does not need to be isolated from the manifold. The aluminum manifold is able to withstand the high temperature of the EGR gases, and consequently, the high temperature of the EGR flange.
However, there are problems associated with these high temperatures if the manifold is comprised of a non-metallic material, such as plastic. These hot gases can damage or destroy a plastic manifold. Therefore, plastic manifolds must be isolated from these hot gases.
Currently, cold tubes are used to introduce the EGR gases into the airflow stream where a plastic manifold is used. The cold tube allows the EGR gases to travel a distance before entering the plastic manifold. However, with use of the cold tube, the gases are not directly introduced into the plastic manifold.
Therefore, it would be desirable to provide an alternative apparatus and method for introducing EGR gases into a manifold that is comprised of a non-metallic material.
In an embodiment of the apparatus of the present invention, an exhaust gas recycle (EGR) isolation flange is provided. The EGR isolation flange includes an annular body that defines a central aperture therethrough and a plurality of bosses. The plurality of bosses extend axially from the body in a direction substantially perpendicular to a plane of the body.
In an embodiment of a method in accordance with the present invention, a method for coupling an exhaust gas recycle (EGR) flange to an isolation flange is provided. The method includes the acts of mating the EGR flange to the isolation flange by receiving an isolation flange boss within a boss receiving aperture of the EGR flange and disposing a seal ring between the EGR flange body and the isolation flange body such that the EGR flange body is physically isolated from the isolation flange body.